<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8"/>
    <title>2-7 !important</title>
    <style>
        #idSelector {
            color: blue; /* 蓝色 */
        }

        .classSelector {
            color: green; /* 绿色 */
        }

        h2 {
            color: red !important; /* 红色 */
        }
    </style>
</head>
<body>
<h2 id="idSelector" class="classSelector">选择器的优先级（特异性）</h2>
</body>
</html>
